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the other hand, the cost of fuel, which usually must be oil or
spirit, is some six times that of the petrol cars, the boiler rarely
receives the attention it ought to, and water cannot be carried for
a longer run than 50 miles at the outside. Electric cars have yet
to fight against the heavy odds of the accumulator weight, not
less than 15 cwts. of which are required to produce the full

Petrol cars holding the market so well, despite numerous
difficulties in working, a typical car has been illustrated in
Fig. 919, of medium size for touring purposes. The early cars
were insufficiently powered, and the demand for starting on and
racing up average inclines has raised the horse-power very con-
siderably : so we have at present:


iVoiturettes or ) smallest cars )
	2 people

/ Light Voitures ) \ or small cars   \
	3 to 4 people

!  Touring and ) large cars    J
	4 to 8 people

Racing cars
	2 people

	Speeds per hour

	I cylinder
	4 to 8
	15 miles

	2 to 3 cylinders
	5 to 10

	4 cylinders
	12 to 30
	30    ,,

	4 to 8 cylinders
	30 to 75

Heavy traffic must ultimately be one of the largest develop-
ments of motor work. At present it is mostly steam-driven,
though petrol driving is adopted for omnibuses.

Referring to Fig. 919, the lower part of the car is called the
' chassis/ and the carriage portion the c carrosserie.' The latter
is shewn at f, as of 'tonneau' form, with back entrance, which,
though compact, is now superseded by the more convenient
' side-entrance ' body. Both give two seats in front, one for the
olriver; and two seats at the back. Often, but not always, there
are two frames: the one marked a, supporting the carriage and
resting on two laminated springs over each axle, carries also the
brake and chain pinion shafts; the second, marked &, supports
the engine, gear case, water tank, &c.; and the two frames are